1. Field of the Invention
This invention relates to a support pole comprising a hollow shaft extending upwardly from a base which is secured to a footing and more particularly to a means for providing a mechanical connection of the shaft to the base.
2. Description of the Related Art
Support poles for supporting lights, etc., thereon are commonly constructed of a metal material such as aluminum or steel. In most instances, the support pole comprises a pole member or shaft which is secured to a base which in turn is secured to a concrete footing. The base is normally comprised of a substantially flat baseplate or plate portion having a generally cylindrical portion extending upwardly therefrom. The base is sometimes comprised of a flat baseplate portion only without a cylindrical portion. When the shaft is comprised of aluminum or steel, the shaft is normally welded to the metal baseplate. If the shaft is constructed of aluminum, the welding operation may weaken the shaft in the area of the weldment which is commonly referred to as a heat affected zone (HAZ).
A typical prior art support pole construction is illustrated in FIG. 2 wherein the numeral 10 refers to a base 10 including a plate portion 12 having a generally cylindrical portion 14 extending upwardly therefrom with the cylindrical portion 14 including a central opening 15 defined by surface 16. The hollow metal shaft 18 is positioned in the central opening 15 of the base 10 so that the lower end 20 of the shaft 18 is spaced above the bottom surface 22 of the plate portion 12 of base 10. The lower end 20 of the shaft 18 is welded to the base 10 at 22. In some cases, the outer surface of the shaft 18 is welded to the upper end of the base 10 by weldment 24. Normally, central opening 15 has a slight taper or draft to facilitate the removal of the base 10 from the mold if the base 10 is a casting. Such draft or taper results in a small gap 23 which makes welding more difficult at quality levels.
Although the prior art method of securing the shaft to the base in FIG. 2 is extensively used in the industry, the same has certain disadvantages. First, two heat affected zones (HAZ) are created due to the weldments 22 and 24. Second, the use of two weldments increases the cost of fabricating the assembly. Third, since the lower end of the shaft 18 is spaced above the bottom surface 22 of the base 10, a taller base 10 is required as a way of transferring the loads away from the weldments.
A support pole is described which includes a horizontally disposed base for attachment to a footing with the base including a plate portion, having a bottom surface, and a generally cylindrical portion extending upwardly therefrom. The base has a central opening formed therein which extends between the upper and lower ends thereof. The plate portion has an annular cut-away portion formed in its bottom surface which communicates with the lower end of the central opening. A hollow metal shaft is inserted into the central opening of the base so that its lower end is substantially flush with the bottom surface of the plate portion. A weldment is provided in the annular cutaway portion which welds the outer surface of the lower end of the shaft to the base. The shaft has an enlarged diameter portion immediately above the upper end of the base. The single weldment and the enlarged diameter portion on the shaft securely attach the shaft to the base. In another embodiment, the cylindrical portion is omitted from the base. Further, the cylindrical portion may be replaced with a square portion to accommodate square shafts.
In some cases, the base will be comprised of a flat baseplate portion without a cylindrical portion.
It is therefore a principal object of the invention to provide an improved support pole.
Still another object of the invention is to provide a mechanical connection for the shaft of the pole to a base which requires only a single weldment.
These and other objects will be apparent to those skilled in the art.